Chemical-mechanical Planarization - Limitations of CMP

Limitations of CMP

There are currently several limitations of CMP that appear during the polishing process requiring optimization of a new technology. In particular, an increase in the wafer metrology is required. In addition, it was discovered that CMP process has several potential defects including stress cracking, delaminating at weak interfaces, and corrosive attacks from slurry chemicals. The oxide polishing process, which is the oldest and most used in today’s industry, has one problem: a lack of end points creates blind spot polishing, making it hard to determine when the desired amount of material has been removed or the desired degree of planarization has been obtained. If the oxide layer has not been sufficiently thinned and/or the desired degree of planarity has not been obtained during this process, then the wafer must be repolished. If the oxide thickness is too thin or too non-uniform, then the wafer must be reworked. Obviously, this method is time-consuming and costly since technicians have to be more attentive while performing this process.